The innovations and related subject matter disclosed herein (collectively referred to as the “disclosure”) pertain to control systems, and more particularly, but not exclusively, to detectors configured to issue an alert or a command to a controller in response to a detected change in state of a given system, with a leak detector configured to respond to a detected leak of a working fluid from a liquid-based heat transfer system being but one example of disclosed detectors and related innovations, and with a flow-rate sensor configured to detect a rate of flow of a fluid through a conduit, for example an optical flow-rate sensor, being but one other example of disclosed sensors and related innovations. Some detectors and control systems are described in relation to cooling systems for electronic devices by way of example. Nonetheless, one or more of the innovations disclosed herein can be suitable for use in a variety of other control-system applications, as will be understood by those of ordinary skill in the art following a review of the present disclosure.
Computer system performance and heat dissipation density continue to increase. Consequently, conventional air-cooling is giving way to liquid-cooling in some computer system applications, including, but not exclusively, server and data center applications. Although commercially available liquid cooling systems are considered to be reliable and to provide known and repeatable performance, an automated approach for detecting an unlikely leak might be desirable in some applications. However, commercially available moisture sensors and leak detectors are not compatible with existing control systems for computer systems.
Also, approaches for monitoring a rate of flow of a fluid through one or more conduits might be desirable in some applications. For example, a rate of heat transfer through a liquid-to-liquid or an air-to-liquid (or a liquid-to-air) heat exchanger can correspond to a rate of flow of a heat transfer medium (e.g., a liquid coolant) through the heat exchanger. As but one other example, a substantial excursion of fluid flow rate through a conduit can indirectly indicate a leak upstream of the conduit, or a change in heat-transfer performance.
However, many commercially available flow-rate sensors are generally considered to be incompatible with existing liquid-cooling systems suitable for computer systems. For example, some known flow-rate sensors are typically too large, too expensive, or both, to be incorporated into liquid-cooling systems suitable for widespread commercialization in connection with cooling systems for computer systems, or other systems.
Accordingly, there remains a need for sensors configured to detect a leak from a liquid cooling system. There also remains a need for a monitoring system configured to initiate an alert responsive to a leak detected by the leak detector. A need also remains for a leak detector configured to be compatible with a control system for a computer system or other computing environment. And, there remains a need for flow-rate sensors configured to detect or sense a rate of flow of a working fluid through a conduit, for example, a portion of a flow path through a portion of a liquid-cooling system. There remains a further need for flow sensors to emit a signal responsive to a detected or a sensed flow rate of the working fluid.
There also remains a need for such sensors to be compatible with existing communications busses, e.g., by using existing communication protocols or by multiplexing over existing communication busses (e.g., an IPMI bus).